What's the technical name for the dish you place under a planters holes that catches water from it? Googling 'dishes' when I look for a gardening water catching dish returns kitchen dishes, when I am looking instead for the gardening ones. I realize I might use some kitchen dishes for this purpose, but I imagine that gardeners have a specific term for this item.
I've always heard and used "saucer", which probably came from the practice of using actual old glass/china saucers under plants. Gardeners tend to be a thrifty lot and have been following the "reuse/recycle" ethos for decades, if not forever. Personally, I've used old saucers, pie tins, layer cake pans, square cake pans, and many other castaways as plant saucers. I have only once purchased a saucer, and that's because it came with the pot.
BTW, in the US the major online retailers agree with this term and typically have these receptacles listed as "plant saucers".
Try googling 'plant pot drip trays' as well, you're more likely to be shown a range of trays suitable for plants rather than china in the kitchen... If you want a decorative outer pot to stand a plant pot in, that's usually called a cache pot. Most of these don't have drainage holes, though some may have a hole with a matching saucer or tray beneath.